Vehicle seat having an electronic control system

ABSTRACT

An electronic control system ( 24 ) for a vehicle seat is provided that includes a seat base ( 12 ), a seat back ( 14 ), an operator input device ( 30 ) and a control circuit ( 26 ). The seat base has a seat back motor ( 34 ) configured to move a seat base forward and backward. The seat back has a seat back motor ( 32 ) configured to adjust an angle of inclination of the seat back. The operator input ( 30 ) device is configured to received operator commands for movement of the vehicle seat. The control circuit is configured to receive the operator commands and to control the seat base motor and the seat back motor. The control circuit is also configured to move the seat base and the seat back at a ratio of approximately 1 degree of inclination to between approximately 1 mm to approximately 4 mm of forward or backward movement of the seat base.

BACKGROUND

Vehicle seats are often adjustable so that various drivers, passengers,and other users can adjust the seat to the individual's desires. Vehicleseats can be adjusted in a number of ways. One of the simplest ways toadjust a vehicle seat is by reclining. Another way to adjust the seat isby moving it forward or backward with respect to a fixed object such as,for example, a dashboard or a steering wheel. Providing the user withthe option of adjusting the vehicle seat as described, allows the usergreater flexibility as well as making the vehicle compatible with alarger number of users.

Often when a user adjusts a vehicle seat by, for example, reclining orinclining, the user will move toward or away from the steering wheel ordashboard. Typically, after reclining or inclining the vehicle seat, theuser will want to adjust the seat forward or backward so that the useris brought back to his or her original position in relation to thesteering wheel or dashboard. Unfortunately, this process has a number ofdisadvantages. For example, if the user is operating the vehicle whileadjusting the seat, the user is not focusing on the task of operatingthe vehicle. The more time the user is spending adjusting the seat, thelonger the user is distracted. Also, many times it is difficult for theuser to gauge where the user's original position was in relation to thesteering wheel or other fixed object.

SUMMARY OF THE INVENTION

According to one exemplary embodiment, an electronic control system fora vehicle seat is provided that includes a seat base, a seat back, anoperator input device and a control circuit. The seat base has a seatback motor configured to move a seat base forward and backward. The seatback has a seat back motor configured to adjust an angle of inclinationof the seat back.

The operator input device is configured to received operator commandsfor movement of the vehicle seat. The control circuit is configured toreceive the operator commands and to control the seat base motor and theseat back motor. The control circuit is also configured to move the seatbase and the seat back at a ratio of approximately 1 degree ofinclination to between approximately 1 mm to approximately 4 mm offorward or backward movement of the seat base.

According to another exemplary embodiment, an electronic control systemfor a vehicle seat includes a seat base, a seat back, an operator inputdevice and a control circuit. The seat base has a seat back motorconfigured to move a seat base forward and backward. The seat back has aseat back motor configured to adjust an angle of inclination of the seatback. The operator input device is configured to received operatorcommands for movement of the vehicle seat. The control circuit isconfigured to receive the operator commands and to control the seat basemotor and the seat back motor. The control circuit includes a voltagedivider circuit configured to provide a first voltage across the seatbase motor and a second voltage across the seat back motor, wherein thefirst and second voltages are different.

According to another exemplary embodiment, a vehicle seat having anelectronic control system includes a track, a seat base coupled to thetrack, a seat back pivotally coupled to the track, seat base and backinput devices, and a control circuit. The seat base has a seat basemotor configured to move the seat base forward and backward. The seatback has a seat back motor configured to adjust an angle of inclinationof the seat back. The seat base input device is configured to receiveoperator commands for movement of the seat base. The seat back inputdevice is configured to receive operator commands for movement of theseat back. The control circuit is configured to receive the operatorcommands and to control the seat base motor and seat back motor. Thecontrol circuit is configured to move both the seat base and the seatback in response to receiving a command from the seat back input deviceand to move the seat base alone in response to receiving a command fromthe seat base input device.

According to one advantageous feature, the control circuit is configuredto move the seat base at a first speed in response to receiving acommand from the seat back input device and to move the seat base at asecond speed faster than the first speed in response to receiving acommand from the seat base input device.

According to another exemplary embodiment, an electronic control systemfor a vehicle seat comprises a seat base motor, a seat back motor, anoperator input device, and a control circuit. The seat base motor isconfigured to move the seat base forward and backward. The seat backmotor is configured to adjust an angle of inclination of the seat back.The operator input device is configured to receive operator commands formovement of the vehicle seat. The control circuit is configured toreceive the operator commands and to control a seat base motor and seatback motor. The control circuit is configured to move both the seat baseand seat back simultaneously at a ratio of approximately 1 degree ofinclination of the seat back to approximately 1.5 millimeters of forwardor backward movement of the seat base.

According to another exemplary embodiment, an electronic control systemfor a vehicle seat includes a seat base motor, a seat back motor, anoperator input device, and a control circuit. The seat base motor isconfigured to move the seat base forward and backward. The seat backmotor is configured to adjust an angle of inclination of the seat back.An operator input device is configured to receive operator commands formovement of the vehicle seat. The control circuit is configured toreceive the operator commands and to control the seat base motor andseat back motor. The control circuit includes a voltage divider circuitconfigured to provide a first voltage across the seat base motor and asecond voltage across the seat back motor, wherein the first and secondvoltages are different.

According to one advantageous feature, the control circuit is configuredto move both the seat base and seat back simultaneously at a ratio ofapproximately 1.5 millimeters of forward or backward movement of theseat base to approximately 1 degree of inclination of the seat back.

According to another advantageous feature, the control circuit providesopen loop control of the seat base motor and the seat back motor.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will become more fully understood from the followingdetailed description, taken in conjunction with the accompanyingdrawings, wherein like reference numerals refer to like parts, and inwhich:

FIG. 1. is schematic drawing of a vehicle seat, according to anexemplary embodiment;

FIG. 2 is a schematic drawing of an electronic control system for avehicle seat, according to an exemplary embodiment;

FIG. 3 is a schematic drawing of an electronic control system for avehicle seat, according to another exemplary embodiment;

FIG. 4 is a schematic drawing of an electronic control system for avehicle seat, according to another exemplary embodiment;

FIG. 5 is a schematic drawing of an electronic control system for avehicle seat, according to another exemplary embodiment; and

FIG. 6 is a schematic drawing of an electronic control system for avehicle seat, according to another exemplary embodiment.

FIG. 7 is a schematic drawing of an electronic control system for avehicle seat, according to another exemplary embodiment.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Referring first to FIG. 1, a vehicle seat 10 is shown in an exemplaryembodiment. Vehicle seat 10 includes a seat base 12 and a seat back 14.Vehicle seat 10 can be a seat such as that disclosed in U.S. ProvisionalApplication No. 60/356,836 entitled “Automotive Seat With Live Back” toHancock et al., filed Feb. 12, 2002, which is incorporated by referenceherein. Seat base 12 and seat back 14 are coupled to a track, such as anadjuster or other mounting member. Seat base 12 includes a seat basemotor (not shown) configured to move the seat base forward and backward,as indicated by arrow 16. Seat back 14 includes a seat back motor (notshown) configured to adjust an angle of inclination, as indicated byarrow 18, of seat back 14. Vehicle seat 10 can further include motorsconfigured to adjust the vertical height of seat base 12 (arrow 20) andthe back of seat base 12 (arrow 22).

An electronic control system 24 for vehicle seat 10 includes a controlcircuit 26, a plurality of motors 28, and an operator input device 30.Motors 28 include seat back motor 32 configured to adjust the angle ofinclination of seat back 14 and seat base motor 34 configured to movethe seat base forward and backward. Motors 28 can be any of a number ofdifferent motor types, such as direct current motors, servo motors,electromagnetic control motors, etc.

Control circuit 26 includes circuit elements needed to drive motors 28and to receive commands from operator input device 30. Control circuit26 can include analog and/or digital circuit elements, and can include adigital processor, such as, a microprocessor, microcontroller,application specific integrated circuit (ASIC), etc. Control circuit 26is configured to drive motors 28 using pulse-width modulated signals,direct current signals, or other control signals.

Operator input device 30 is shown in schematic form having a seat backbutton 36 and a seat base button 38. Each of buttons 36 and 38 instructsthe user that the button is for the control of seat back 14 and seatbase 12, respectively, by an applicable icon or, in this exemplary case,by shaping the button to correspond generally to a seat base or a seatback. In this manner, the user understands which button is for controlof which portion of vehicle seat 10. Seat back button 36 is configuredto be moved forward and backward as indicated by arrow 40 to adjust theangle of inclination of seat back 14 via control circuit 26 and seatback motor 32. Seat base button 38 is configured to adjust the forwardand backward (fore-aft) position of seat 12 as indicated by arrow 42 andis further configured to move the front and back of seat base 12 upwardand downward, selectively, as indicated by arrows 44 and 46. Operatorinput device 30 is an “8-way” switch in this exemplary embodiment, butmay alternatively be a 6-way switch, or other switches.

Electronic control system 24 is configured in this exemplary embodimentto receive operator commands via input device 30 and to control motors28. According to one advantageous embodiment, control circuit 26includes a “power glide” feature wherein seat base 12 and seat back 14are both moved in response to receiving a command from seat back button36. Desirably, control circuit 26 is configured to move seat base 12 ata slower speed when receiving a command from seat back button 36 thanwhen moving seat base 12 in response to a command from seat base button38. Generally, it is desirable to move the seat base 12 a distance thatis proportional to the distance which the seat back 14 has moved. Oneway to accomplish this is to simultaneously move seat base 12 and seatback 14 so that seat base 12 moves at a speed that is proportional tothe speed of seat back 14. It has been found that a desirablerelationship of movement between seat back 14 and seat base 12 toprovide a “glide” effect includes moving seat base 12 and seat back 14simultaneously at a ratio of approximately 1.5 millimeters (mm) offorward or backward movement of seat base 12 to approximately one degreeof inclination of seat back 14. The ratio may alternatively be any valuebetween 1 mm and 4 mm, or desirably between 1.5 mm and 3 mm, of forwardor backward movement of seat base 12 to approximately one degree ofinclination of seat back 14.

The “power glide” may provide a number of desirable effects. Forexample, the “power glide” feature of moving both seat base 12 and seatback 14 simultaneously in response to actuation of seat back button 36may provide improved user comfort and avoids multiple repositioningcommands which would otherwise be needed to place the vehicle seat in anoptimal seating position. In the situation where the user is driving thevehicle, the “power glide” feature also may advantageously allow theuser to keep his or her hands on the steering wheel and eyes on the roadin relatively the same position as before the seat back 14 was reclined.Also, the “power glide” feature may keep the user's lower back againstthe seat during and after recline of seat back 14 without the userhaving to change their posture. In vehicles equipped with a personaloccupant detection system, the system may be more robust because the“power glide” feature may keep the user in and against the seat. Itshould be understood that the present application is not limited toembodiments that either do or do not produce one or more of the abovedesirable effects.

In this embodiment, movement of seat base 12 during the “power glide”movement is at a speed slower than that of movement outside of the“power glide” feature. Thus, if the user actuates seat base button 38along the direction of arrow 42, seat base 12 will move at a speedfaster than that during movement according to the power glide feature.Likewise, movement of seat base 12 in the direction of arrows 20 and 22will also provide the faster movement. In this exemplary embodiment,seat back 14 cannot be moved without movement of seat base 12, unlessseat back 14 has reached a mechanical or preset limit to its angle ofinclination. Alternatively, seat back 14 cannot be moved withoutmovement of seat base 12, unless seat base 12 has reached a mechanicalor preset limit to the range of forward and backward movement.

Typically, a vehicle seat is mounted in a vehicle so that the seat base12 is not horizontal. For example, a vehicle seat in an automobile maybe mounted so that the seat base 12 has an approximately 6 degreeforward incline. In this situation, the seat base 12 will be assisted bygravity as it moves backward and will be hindered by gravity as it movesforward. This may cause the seat base 12 to move backward at a fasterspeed than it moves forward. Accordingly, in one embodiment, theelectronic control system 24 may include a measuring device (not shown)configured to measure the speed and/or position of seat back 14 as theangle of inclination changes. The speed and/or position of the seat back14 is input into control circuit 26 so that the speed and/or position ofthe seat base 12 can be controlled to be proportional to the speed ofthe seat back 14. This may be accomplished using a proportional feedbackcontrol loop. The measuring device may be a potentiometer, Hall effectsensor, or other like devices that can measure the speed and/or positionof seat back 14. Alternatively, it may be desirable to measure the speedof the seat base 12 as it moves and control the speed of the seat back14 to maintain the desired proportional relationship between the speedof the two devices.

Referring now to FIG. 2, an exemplary embodiment of control circuit 26will now be described as control circuit 50. Control circuit 50 includesfour switches, switch 1, switch 2, switch 3, and switch 4. Controlcircuit 50 further includes relay 1, relay 2, and a resistor R. ResistorR has a resistance of between 1 and 3 Ohms, desirably 2 Ohms, and israted for approximately 50 watts, but may alternatively have otherresistance and power characteristics. Seat back motor 32 (or reclinermotor) is disposed parallel with resistor R and seat base motor 34 (orcushion motor). Relay 1 is configured to switch one terminal of seatbase 34 between resistor R and switch 3. Relay 2 is configured to switcha second terminal of seat base motor 34 between switch 2 and switch 4.Each of switches 1, 2, 3, and 4 is configured to select either batteryor ground from a vehicle power source to motors 32, 34 and relays 1, 2.Switches 1 and 2 are connected to seat back button 36 and cannot beactivated at the same time. Switches 3 and 4 are connected to seat basebutton 38 and cannot be activated at the same time. When recliner button36 is moved forward (FIG. 1, arrow 40), switch 1 connects the battery tothe terminal between motor 32 and resistor R to drive seat back 14forward. The power from the battery is provided through resistor R toseat base motor 34 to drive seat base motor 34 at a speed ofapproximately 1.5 millimeters per degree of inclination of seat back 14.Thus, resistor R is part of a voltage divider network configured toprovide a first voltage across motor 32 and a second, smaller voltageacross motor 34. In response, motor 32 moves at a regular speed andmotor 34 moves at a reduced speed from its regular speed. When seat backbutton 36 is moved backward (FIG. 1, arrow 40), switch 2 provides powerfrom the battery to the other terminal of seat back motor 32 to driveseat back 14 backward. Switch 2 also provides the battery power to seatbase motor 34 through relay 2 and relay 1 and resistor R to move seatbase 12 forward at a speed of 1.5 millimeters per degree of inclinationof seat back 14.

When seat base button 38 is moved backward (FIG. 1, arrow 42), switch 3provides battery power to a coil of relay 1 which switches the input toseat base motor 34 from resistor R to switch 3 and switches the otherterminal of seat base motor 34 from switch 2 to switch 4 via a coil ofrelay 2. Since vehicle power is provided directly through motor 34(i.e., not via resistor R), motor 34 is driven at a faster, regularspeed than when power was provided through resistor R. Seat base motor34 drives seat base 12 backward and seat back motor 32 is not driven,whereby seat back 14 does not move.

When seat base button 38 is moved forward (FIG. 1, arrow 42), switch 4provides power from the battery through the coils of relay 2 and relay 1to connect the terminals of seat base motor 34 to switches 3 and 4.Power returns through switch 3 to ground, thereby driving seat base 34in the forward direction at the faster, regular speed. When switches 1and 3 are activated simultaneously, indicating a command to move seatback forward and seat base 12 backward, relays 1 and 2 are activated,and both motors 32 and 34 are actuated at full speed to carry out theuser command. If switches 1 and 4 are activated simultaneously, againrelays 1 and 2 are activated such that both commands are carried out atfull speed. Likewise, if switches 2 and 3 or switches 2 and 4 areactivated (corresponding to user commands of seat back 14 backward andseat base 12 backward, and seat back 14 backward and seat base 12forward, respectively), movement of motors 32 and 34 is carried out atregular speed, because resistor R is not included in the circuit forproviding power from battery to ground through motors 32 and 34.

Referring now to FIG. 3, a schematic diagram of a control circuit 52according to an alternative embodiment is shown. Control circuit 52 isthe same as control circuit 50, except that switch 3 is coupled to thecoil of relay 1 through a diode 54 and switch 4 is coupled to a coil ofrelay 2 through a diode 56. The anodes of diodes 54 and 56 are coupledto switches 3 and 4, respectively, and the cathodes of diodes 54 and 56are coupled together and to the coils of relays 1 and 2. The oppositeends of the coils of relays 1 and 2 are coupled to ground. Diodes 54 and56 protect the relay coils from turn-on and turn-off voltage transientsfrom motor 34 (also referred to as inductive kick).

Referring now to FIG. 4, a further exemplary embodiment of controlcircuit 26 is shown as control circuit 58. In this embodiment, relays 1and 2 of the embodiments of FIGS. 2 and 3 are replaced with twoadditional switches, switch 3′ and switch 4′. Each of switches 1, 2, 3,3′, 4, and 4′ are illustrated in this drawing and in the other drawingsof the present application in their rest or sleep state, also called thenon-activated state. Seat back button 36 is illustrated and includesarrow 40 indicating that forward movement of button 36 corresponds toactuation of switch 1 and backward movement of button 36 corresponds toactuation of switch 2. Likewise, seat base button 38 is illustratedalong with arrow 42, indicating that backward movement of button 38corresponds to actuation of switches 3 and 3′ and forward movement ofbutton 38 corresponds to actuation of switches 4 and 4′.

In this embodiment, resistor R is coupled between switch 1 and switch 3.Switch 3 selectively couples the other terminal of switch 3 betweenground and switch 4′. Switch 4′ selectively couples switch 3 to eitherbattery or motor 34. The other terminal of motor 34 is coupled to switch3′. Switch 3′ couples the other terminal of motor 34 selectively to thevehicle battery or to switch 4. Switch 4 couples switch 3′ selectivelyto either ground or switch 2. As in the embodiments of FIGS. 2 and 3,recliner motor 32 is coupled between switch 1 and switch 2, and switches1 and 2 selectively couple either battery or ground to motor 32 to drivemotor 32 in the forward or backward direction.

In operation, switches 1 and 2 are connected to button 36 and cannot beactivated at the same time. Switches 3 and 3′ are connected together andare activated by backward movement of button 38. Switches 4 and 4′ areconnected together and are activated by forward movement of button 38.When button 36 is moved forward, switch 1 is activated to providebattery power through motor 32 and to resistor R, switch 3, switch 4′,through motor 34, to switch 3′, to switch 4, to switch 2 and to ground.In this manner, motor 34 is driven at a reduced speed, preferably 1.5millimeters per degree movement of motor 32.

When button 36 is moved backward, switch 2 is actuated to couple batterypower through motor 32 to switch 1 to ground and to provide batterypower through switch 2 to switch 4 to switch 3′ through motor 34 toswitch 4′ to switch 3 through resistor R to switch 1 to ground. In thismanner, seat back 36 moves backward and seat base 12 moves forward at areduced speed.

When button 38 is moved forward, switches 4 and 4′ are activated whereinpower is provided from switch 4′ through motor 34 to switch 3′ to switch4 to ground, thereby moving motor 34 forward at regular speed. If button38 is moved back, switches 3 and 3′ are activated, wherein power isprovided from the vehicle battery to switch 3′ through motor 34 toswitch 4′ to switch 3 to ground, thereby moving motor 34 backward atregular speed. If buttons 36 and 38 are both moved forward, motor 32moves forward at full speed and motor 34 moves forward at full speed. Ifbuttons 36 and 38 are moved backward or some combination of forward andbackward, motors 32 and 34 are moved together simultaneously at regularspeed.

Referring now to FIG. 5, another exemplary embodiment of control circuit26 is shown as control circuit 60. In this embodiment, switches 3 and 3′and switches 4 and 4′ of the embodiment of FIG. 4 are replaced with3-way switches, wherein switch 3 couples one terminal of motor 34 tobattery power, to ground, or to resistor R. Likewise, switch 4 isconfigured to couple the other terminal of motor 34 to battery power, toground, or to the terminal between switch 2 and motor 32. Motors 32 and34 are disposed in parallel with one terminal shared by resistor R andmotor 32. When button 38 is actuated alone, switch 3 provides batterypower to motor 34 and switch 4 provides a closed circuit to ground. Whenbutton 38 is actuated forward alone, battery power is provided throughswitch 4 to motor 34 and switch 3 provides a closed circuit to ground.When seat back button 36 is actuated forward or backward, switches 3 and4 are in their rest state, wherein power is provided to motor 34 onlythrough resistor R, thereby moving motor 34 at a slower speed than whenbutton 38 is actuated alone. Further, when button 38 is actuatedsimultaneously with button 36, power is provided separately to motors 32and 34, and not through resistor R, such that both motors are moved attheir full, regular speeds in both directions.

Notably, in the embodiments of FIGS. 2–5, resistor R comprises a portionof a voltage divider circuit configured to provide a first voltageacross seat base motor 34 and a second voltage across seat back motor32, wherein the two voltages are different. The difference in voltagescan be used to drive motor 34 at a different speed than motor 32,preferably at a slower speed, to provide a power glide feature. Also ofnote, the circuits of FIGS. 2–5 provide open loop control, wherein nofeedback is provided as to the position of motors 32 and 34. Accordingto one alternative embodiment, feedback may be provided to furtherimprove positioning of motors 32 and 34.

Referring now to FIG. 6, an alternative embodiment of control circuit 26is shown as control circuit 62. In this embodiment, a digital processor,preferably a microprocessor 64 provides control signals to seat basemotor 34 and/or seat back motor 32 (not shown). In this embodiment, apulse-width modulated control signal is provided at microprocessoroutput 66 to a transistor 68, which is a temperature-protected fieldeffect transistor (FET) in this exemplary embodiment, but mayalternatively be other transistors. Transistor 68 is a BTS282Ztransistor manufactured by Infineon Technologies, Munich Germany. Thetemperature protection provides the advantage of protecting the FET fromexcess heat due to prolonged use or continuous high current use. Thesource of transistor 68 is coupled to ground and the drain oftransmitter 68 is coupled to one input of each of a plurality of relays70, 72. Relays 70 and 72 are actuated by digital outputs frommicroprocessor 64 indicated at output 74 and output 76. When seat basebutton 38 (FIG. 1) is moved forward or backward, digital signals areprovided to output 74 or output 76, respectively, to drive relay 70 or72 to provide power from a vehicle battery source to the motor 34. Whenseat back button 36 is actuated forward and backward alone, in additionto moving seat back 14, output 74 or 76 is actuated, and an adjustablecontrol signal is provided from microprocessor 64 via output 66 andtransistor 68 to provide an amount of power to motor 34 less than thatwhen seat base button 38 is actuated. Consequently, in one embodiment,control circuit 64 is configured to control motor 34 at a slower speedwhen seat back button 36 is actuated than when seat base button 38 isactuated. Further, the speed ratio is preferably 1.5 millimeters ofmovement of seat base 12 for every one degree of movement of seat back14. A diode 78 is provided between a vehicle battery source andtransistor 68 for protection of transistor 68 from voltage spikes in thebattery.

Referring now to FIG. 7, an alternative embodiment of control circuit 26is shown as control circuit 63. Control circuit 63 is an example of acontrol circuit 26 that may be used on a vehicle seat which includesseat base 12 and seat back 14. Seat base 12 includes a seat base motor34 configured to move the seat base forward and backward as indicated byarrow 16. Seat back 14 includes a seat back motor 32 configured toadjust an angle of inclination, as indicated by arrow 18, of seat back14. Seat back 14 also includes tension motor 90 configured to adjust thelumbar portion of the vehicle seat as indicated by arrow 92. Seat base12 includes front vertical adjustment motor 86 and rear verticaladjustment motor 88 configured to adjust the vertical height of thefront and rear portions of seat base 12 as shown by arrows 20 and 22,respectively. A potentiometer 84 is also included which measures thespeed at which seat base 12 moves as seat back motor 32 changes theangle of inclination.

In operation, control circuit 63 moves seat base 12 proportionally toseat back 14 at a ratio of between approximately 1 mm to approximately 4mm, or desirably, between approximately 1.5 mm to approximately 3 mm, toapproximately 1 degree change in the angle of inclination. In thisembodiment, control module 82 detects when the seat back motor 32 isactivated and powers seat base motor 34 so that seat base 12 moves adistance corresponding to the above ratio. This may be done usingcontrol module 82 to maintain the speed of seat base 12 at apreconfigured fixed rate so that the position of the seat base 12 isgenerally proportional to the position of seat back 14 as seat back 14moves. The speed of seat base 12 may be measured using potentiometer 84.The fixed rate is generally preprogrammed into the control module 82,but alternatively the fixed rate may be set after it leaves themanufacturer. In general, the seat base 12 moves forward when the seatback 14 reclines, and the seat base 12 moves backward when the seat back14 inclines. Also, in some situations, to counter the effects ofgravity, control module 82 may be configured to move seat base 12backward at a speed that is slower than if seat base 12 was movingforward. Control circuit 63 may also be configured so that seat basemotor 34 may be activated alone, in which case, seat base 12 would moveat a speed that is faster than the speed at which seat base 12 moves incombination with seat back 14.

In an alternative embodiment, potentiometer 84 or a similar measuringdevice may be used to measure the position of seat back 14. The positioncould then be used as the set point for a feed back control loop thatmaintains the position of seat base 12 proportional to the position ofseat back 14 as seat back 14 is adjusted. This may be accomplished byusing another potentiometer to measure the position of seat base 12 sothat the position of seat base 12 is continually compared to theposition of seat back 14 as it moves and seat back 12 is continuallyadjusted accordingly. Other alternatives and configurations may be usedwithout departing from the scope and spirit of the present disclosure.

1. An electronic control system for a vehicle seat comprises: a seatbase motor configured to move a seat base forward and backward; a seatback motor configured to adjust an angle of inclination of a seat back;an operator input device configured to receive operator commands formovement of the vehicle seat; and a control circuit configured toreceive the operator commands and to control the seat base motor andseat back motor; wherein the control circuit is configured to move theseat base and the seat back at a ratio of approximately 1 degree ofinclination to between approximately 1 mm to approximately 4 mm offorward or backward movement of the seat base.
 2. The electronic controlsystem of claim 1 wherein the control system is configured to move theseat back and seat base simultaneously at a ratio of approximately1degree of inclination to between approximately 1.5 mm to approximately3 mm of forward or backward movement of the seat base.
 3. The electroniccontrol system of claim 1 wherein the ratio is approximately 1 degree ofinclination to approximately 1.5 mm of forward or backward movement ofthe seat base.
 4. The electronic control system of claim 1 wherein theseat base moves at a first speed in response to receiving an operatorcommand for movement of the seat back and the seat base moves at asecond speed in response to receiving an operator command for movementof the seat base alone, wherein the first and second speeds aredifferent.
 5. The electronic control system of claim 4 wherein the firstspeed is less than the second speed.
 6. The electronic control system ofclaim 1 wherein the seat back can be adjusted through a range of motionso that for a portion of the range of motion the seat back cannot beadjusted without movement of the seat base.
 7. The electronic controlsystem of claim 1 wherein the control circuit is configured to move theseat base generally forward in response to an operator command torecline the seat back and to move the seat base generally backward inresponse to an operator command to incline the seat back.
 8. Anelectronic control system for a vehicle seat comprising: a seat basemotor configured to move a seat base forward and backward; a seat backmotor configured to adjust an angle of inclination of a seat back; anoperator input device configured to receive operator commands formovement of the vehicle seat; and a control circuit configured toreceive the operator commands and to control the seat base motor andseat back motor; wherein the control circuit includes a voltage dividercircuit configured to provide a first voltage across the seat base motorand a second voltage across the seat back motor, wherein the first andsecond voltages are different.
 9. The electronic control system of claim8 wherein the control circuit is configured to move both the seat baseand the seat back simultaneously at a ratio of approximately 1 degree ofinclination to between approximately 1.5 mm to approximately 3mm offorward or backward movement of the seat base.
 10. The electroniccontrol system of claim 8 wherein the first voltage is less than thesecond voltage.
 11. The electronic control system of claim 8 wherein theseat base moves at a first speed in response to receiving an operatorcommand for movement of the seat back and the seat base moves at asecond speed in response to receiving an operator command for movementof the seat base alone, wherein the first speed is less than the secondspeed.
 12. The electronic control system of claim 8 wherein the seatback can be adjusted through a range of motion so that for a portion ofthe range of motion the seat back cannot be adjusted without movement ofthe seat base.
 13. The electronic control system of claim 8 wherein thecontrol circuit is configured to move the seat base generally forward inresponse to an operator command to recline the seat back and to move theseat base generally backward in response to an operator command toincline the seat back.
 14. A vehicle seat having an electronic controlsystem comprising: a track; a seat base coupled to the track; a seatback pivotally coupled to the track; a seat base input device configuredto receive operator commands for movement of the seat base; a seat backinput device configured to receive operator commands for movement of theseat back; a control circuit configured to receive the operator commandsfrom one or both the seat base input device and the seat back inputdevice and to control the seat base motor and seat back motor; a seatbase motor configured to move the seat base forward and backward; and aseat back motor configured to adjust an angle of inclination of the seatback; wherein the control circuit is configured to move the seat baseand the seat back in response to receiving a command from the seat backinput device; and wherein the control circuit is configured to move theseat base alone in response to receiving a command from the seat baseinput device.
 15. The vehicle seat of claim 14 wherein the controlcircuit is configured to move the seat base substantially proportionalto the movement of the seat back when the seat base and seat back areboth moving.
 16. The vehicle seat of claim 15 further comprising apotentiometer that measures the position of the seat back, wherein thecontrol circuit is configured to maintain the position of the seat basesubstantially proportional to the position of the seat back.
 17. Thevehicle seat of claim 15 wherein the control circuit is configured tomove both the seat base and the seat back at a ratio of approximately 1degree of inclination to between approximately 1.5 mm to approximately 3mm of forward or backward movement of the seat base.
 18. The vehicleseat of claim 14 wherein the seat base moves at a first speed inresponse to receiving an operator command for movement of the seat backand the seat base moves at a second speed in response to receiving anoperator command for movement of the seat base alone, wherein the firstspeed is less than the second speed.
 19. The vehicle seat of claim 14wherein the control circuit is configured to move the seat basegenerally forward in response to an operator command to pivot the seatback backward and to move the seat base generally backward in responseto an operator command to pivot the seat back forward.
 20. The vehicleseat of claim 14 wherein the control circuit includes a microprocessor.